Add the sauce ingredients to a small bowl and whisk together to combine. Set aside.
If using tofu, heat a small amount of oil in a large skillet over medium-high heat. Place the tofu strips into the skillet and cook 3-5 minutes on each side, until golden brown. Transfer to a paper-towel-lined plate and set aside.
Fill a large saucepan or stock pot with water. Bring to a boil and remove from heat. Add the noodles and allow them to soak until just a little firm -- think one step ahead of al dente. This normally takes about 8-10 minutes, but since different brands may vary, refer to your noodle package instructions. Once the noodles are done soaking, drain them in a colander and rinse with cold water.
Separate the baby bok choy into individual leaves and slice each one lengthwise into 2 or 3 strips.
Place oil in a wok over medium-high heat. Add the garlic and baby bok choy. Stir fry until the bok choy just starts to wilt and turns deep green, about a minute.
Add the noodles and sauce to the wok. Stir fry until the sauce thickens and the noodles are tender, about 3 minutes.
If you're using eggs, push the noodles to the side of the wok to create a little space. If the wok looks a bit dry at this point you can add another splash of oil. Add the eggs into the space you've created and break them up with a spatula; scramble for about a minute. Do your best to keep the eggs separated from the noodles until they're cooked.
Add the scallions and tofu to the wok. Stir fry everything for another 30 seconds or so, just to get everything hot and the flavors blended. Remove from heat.
Divide the noodles onto plates. Top with peanuts and bean sprouts.
If you're not into baby bok choy, or it just isn't available, feel free to sub other veggies. Snow peas, carrots, baby corn and broccoli all work great. You'll need about 3 cups of whatever vegetables you use. Any neutral-flavored cooking oil that you have on hand can be used for this recipe.